Electric plug



June 7, 1938. A. E. GRANT ELECTRIC PLUG Filed se t. 50, 1955 2 Sheets-Sheet 1 June 7, 1938. \A. E. GRANT ELECTRIC PLUG Filed Sept. 30, 1935 2 Sheets-Sheet 2 Patented June 7, 1938 UNITED STATES FATE ELECTRIC PLUG New York, N. Y.

Application September 30, 1935, Serial No. 42,762

9 Claims.

My invention relates to wiring devices and more particularly to devices commonly known as heater plugs which are employed. to connect current supply wires in circuit with electric heating appliances such as sadirons, waflle irons, bread toasters, etc.

Heretofore plugs of this character have usually embodied a casing formed of a plurality of comating parts secured together by means of screws, bolts, or other metallic fastening devices. A principal object of my invention is to provide an improved heater plug in which the molded insulated casing is in one piece.

Another principal object of my invention is to provide an improved heater plug embodying a switch, the actuator for the switch being conveniently located adjacent a shoulder of the easing at the end of the plug opposite the contact terminals.

A further object consists in providing an improved plug of this character in which the several parts are compactly and conveniently arranged in combination to facilitate assembly and to obtain a sturdy and well insulated devicefor the purpose. Other and further objects will appear from the following specification.

Referring to the drawings which form a part hereof,

Figure 1 is a side elevation of a heater plug embodying the features of my invention.

Figure 2 is an edge elevation of the device.

Figure 3 is a cross sectional view taken on line 33 of Figure 2.

Figure 4 is a cross sectional view taken on line 4-4 of Figure 3.

Figure 5 is an elevation of the interior subassembly of the device comprising the insulating block conductors, switch and contacts.

shown in Figure 5.

Figure 7 is an elevational view of the resilient closure for the upper end of the casing together with the wire guard retained thereby.

Figure 8 is a plan view of the closure shown in Figure 7.

Figure 9 is a cross sectional view of the molded insulated housing, and

Figure '10 is a plan view thereof. I 50 The insulating casing l5 consists of a deep molded shell of plastic composition having edge flanges l6 and side flanges I! adjacent its top. The edge flanges are formed to provide a manual grip useful in withdrawing the plug to disconnect it and the side fianges define shoulders 18-48 Figure 6 is a plan view of the sub-assembly on'opposite sides of the casing forengagement by the spring metal closurecap 60.

A slot extending downwardly from the top of the-casing wall at 20 serves to accommodate the outwardly extending actuating lever arm 5| of an internal switch. The lower end wall ofthe casing is apertured at 2I- -2l to receive the contact prongs of an appliancewith which it may be. desired to make connection and the interior walls of the casing are molded to provide suitable shoulders and abutments for positioning and retaining the internal parts of the device. the housing is readily molded in one piece and is of a conveniently handy size and shape.

The interior parts of the device constitute a sub-assembly 25 (see Figure '5), the combined elements of which are adapted to be dropped into the casing and to closely fit therein. The assembly comprises a molded block 26 of insulating material, such as porcelain, to the lower end of which contact clips Hand 28, spacedto register with the openings 2!, are respectively secured by the eyelets 29 and 3t. One jaw member of the clip 21 is extended above the eyelet 29 and carries a binding screw 3] to which one of the current supply wires 32 may be connected. A binding screw 33 for the other supply. wire is carried on the opposite side of the block by a conductor piece 3d which, in turn, is afiixed. to the block by means of an eyelet 35. V

The conductor piece 34 is extended into a recess formed in one side of the block at 36 and is there angularly bent to afford a switch contact 40. A similarly shaped-contact M is carried on the opposite side of the block and is integral with a conductor piece 42 which is secured in position and held against clip 28 by means of the eyelet 30. and 4! are adapted to be bridged by the swinging switch member 45.

From the foregoing it willf be obvious that one side of the circuit through the plug is carried through the lead-in wire'32 directly to the clip contact 21 and that the circuit on the other side of the plug traverses the conductor piece 34, switchmember and thence through conductor piece 42 to the other clip contact 28.

Thus formed,

These switch contacts 40 V p The upper margin of the recess 36in the block defines an arm 41; the outer end of which is perforate to retain a long eyelet 48 in which the bridging switch member 45 is free to swivel 'in making and breaking contact with the contacts 46 and AI.

The swinging switch member 45 is a substantially rectangular band of conducting metal, the

upper side of which extends through the eyelet 48 and the lower side of which is formed to provide an inwardly extending lug 45 to retainone end of the coil spring 49. The other end of the switch spring is securely anchored to the short arm of the actuating lever 50 which is fulcrumed on eyelet 48, the long arm 50 of the lever extending outwardly in position to register with the slot 20 in the housing.

In Figures 3, 4 and 5 the switch is shown in conducting position, the off position of the switch being shown in the broken lines in Figure 3. The operation of the switch is very positive and its action is instantaneous. When the knurled end of the actuator arm 50 is elevated, the spring is compressed and moved outwardly until its axis is parallel with the sides of switch member 45. Immediately the spring is carried past center it re-expands, swiveling the switch member into the position shown in dotted lines of Figure 3, and breaking the circuit between the contacts. Reverse movement of the actuator operates to snap the switch member into bridging position in the same manner.

The switch movement is a usual one and no claim is made to the switch construction beyond its location in respect to the one piece casing and its relation to the other parts of the device.

The remaining assembly comprises the spring metal closure cap and the helical wire guard 65. The cap consists of a stamping having a hole formed therethrough at El to thread over the wire guard and the supply wires 32, the margins 62 of the hole being bossed. The long edge on one side of the cap is flanged inwardly at 63 and the opposite edge is provided with an inward bead 64 adapted to engage under the shoulders it of the casing shell. The wire guard is of conventional construction and its larger convolutions are extended through the hole 6| under the boss 62.

To wire the device, the wire guard and closure cap are first threaded over the current supply wires. The ends of the wires are then respectively secured under the binding screws, the adjacent portions of the wires being laid in the strain relieving grooves 25' formed in the block. The entire assembly 25 is then dropped into the casing andthe inward flange B3 of the cap is hooked under one of the casing shoulders it. Using this abutment of parts as a fulcrum, the cap is hinged over the top of the casing until the cap bead 64 snaps into engagement under the opposite casing shoulder. During this movement, the larger convolutions of the spring wire guard on the under side of the cap are compressed against the top of the block, thereby tending to lift the cap and holding the cap bead and flange securely against the casing shoulders.

To take down the assembly, it is only necessary to lift the bead of the cap from under the casing shoulder, whereupon the cap may be swung off and the assembly 25 may be freely removed.

Constructed and assembled as above set forth, I have found the device affords superior insulation and long wear. The location of the switch lever has proved most convenient and the sturdy assembly of the parts is simple and inexpensive to effect. 5

Having thus described my invention, I claim:

1. A heater plug comprising a deep molded casing of insulating material having exterior shoulders formed on its opposite sides adjacent its top, a closure cap of resilient metal adapted to fit over the top of the casing and havinginwardly extending edge portions adapted to engage said shoulders, conducting means carried within the casing, contacts connected with said conducting means, said cap being perforate to admit current supply wires for connection to said means, and resilient means exerting an upward pressure on said cap to hold the edge portions thereof in engagement with said shoulders, said resilient means comprising inner convolutions of a helical wire guard extending through the cap perforation.

2. A heater plug comprising a block of insulating material and spaced contact clips carried thereby, binding terminals and conducting means carried by'the block and connected to said contacts, a switch in circuit with said means, said switch havingan actuator extending outwardly adjacent an upper corner of said block, a casing comprising a deep molded shell of insulating material adapted to receive the block with the parts carried thereby and having apertures in its bottom wall spaced to register with said contacts; said casing having exterior shoulders formed on opposite sides thereof adjacent its upper open end and having a slot formed in the wall thereof to accommodate said actuator, said slot extending downwardly from the top of the casing; a closure cap for the upper end of the casing, said cap having an opening therethru for current supply wires and a helical wire guard for surrounding said wires, said cap also having inwardly extending edge portions adapted to engage under the exterior casing shoulders, the inner convolutions of said wire guard being larger than the opening in the cap and compressed between said block and the under side of the cap to hold the cap edge portions in engagement with said shoulders.

3. A heater plug comprising a deep molded casing. of insulating material having exterior shoulders formed on opposite sides thereof adjacent its top, a perforate closure cap of spring metal adapted to fit over the top of the casing and having inwardly extending edge portions adapted to engage said shoulders, a resilient helical wire guard extending thru the perforate area of the cap, the inner convolutions of said guard being larger than the cap perforation and compressed between the cap and the internal parts of the device to exert an upward pressure on said cap to hold the edge portions thereof in engagement with said casing shoulders.

4. A heater plug consisting of a one-piece casing of molded insulated material, a removable closure cap for said casing and a wire guard carried thereby, a sub-assembly nested in said casing in a manner to be freely removable therefrom and retained therein by said cap and guard, said sub-assembly comprising a block of insulating material and contacts carried thereby in insulated relation to each other, and conducting means carried by the block and respectively connected to said contacts, said conducting means comprising a switch.

5. A heater plug comprising a deep molded casing of insulating material having exterior shoulders formed on its opposite sides adjacent its top, a closure cap of resilient metal adapted to fit over the top of the casing and having inwardly extending edge portions adapted to engage said shoulders, conducting means carried within the casing, contacts connected with said conducting means, said cap being perforate to admit current supp-1y wires for connection to said means, and resilient means exerting an upward pressure on said cap to hold the edge portions thereof in engagement with said shoulders, said resilient means comprising an integral inner portion of a guard for said current supply wires extending through the cap perforation.

6. A heater plug comprising a block of insulating material and spaced contact clips carried thereby, binding terminals and conducting means carried by the block and connected to said contacts, a casing comprising a deep molded shell of insulating material adapted to receive the block with the parts carried thereby and having apertures in its bottom wall spaced to register with said contacts; said casing having exterior shoulders formed on opposite sides thereof adjacent its upper open end, a closure cap for the upper end of the casing, said cap having an opening therethru for current supply wires and a resilient guard for surrounding said wires, said cap also having inwardly extending edge portions adapted to engage under the exterior casing shoulders, the inner portion of said resilient guard being larger than the opening in the cap and compressed between said block and the under side of the cap to hold the cap edge portions in engagement with said shoulders.

'7. A heater plug comprising a deep molded casing of insulating material having exterior shoulders formed on opposite sides thereof adjacent its top, a perforate closure cap of spring metal adapted to fit over the top of the casing and having inwardly extending edge portions adapted to engage said shoulders, a resilient guard for current supply wires extending through the perforate area of the cap, the inner portion of said guard being of greater diameter than the cap perforation and compressed between the cap and the internal parts of the device to exert an upward pressure on the cap and hold the edge portions thereof in engagement with the casing shoulders.

8. A heater plug comprising a one-piece casing of insulating material, a sub-assembly nested in the casing, a removable closure cap for the casing, and resilient means compressed between the subassembly and the cap to hold the sub-assembly firmly nested in the casing, said means comprising inner convolutions of a helical spring extending through the cap and for a considerable distance exteriorly thereof to provide a flexible guard for current supply wires.

9. A plug of the character described comprising a casing of insulating material, a sub-assembly nested in the casing, said sub-assembly comprising a block of insulating material and contacts carried thereby and conducting means carried by the block and respectively connected to said contacts, a removable closure cap for the casing, said cap beingperforate to admit current supply wires for connection to said means, and resili ent means compressed between the sub-assembly and the cap to hold the sub-assembly firmly nested in the casing, said resilient means comprising inner convolutions of a helical spring extending through the cap perforation and serving as a flexible guard for said wires.

ALBERT E. GRANT. 

